The invention relates to a process and to a station for changing product in an installation for spraying coating product.
It is known, for example from EP-A-0 274 322, to use a reservoir, mounted at the end of an arm of a multi-axis robot, to supply coating product to a pneumatic or rotary sprayer supported by this arm, in particular in the case of an installation for spraying an electrically conducting coating product by means of a sprayer of electrostatic type. This state of the art provides using a sprayer fixed on the arm of the robot, cleaning it and filling it with fresh coating product as a function of needs. According to a first variant, the reservoir is removably mounted on the sprayer and a plurality of reservoirs are used as a function of the coating product chosen. According to a second variant, two reservoirs are used alternately.
In any case, it is necessary to clean the sprayer, which is permanently mounted on the arm of the robot, and prime it with fresh coating product. These operations of rinsing and priming of the sprayer are relatively long, while the time allocated for changing coating product tends to decrease. In effect, in the case of an automobile vehicle production line, the tendency is to increase the production rates or the speeds of advance of the conveyors, which may be of the regularly advancing type or of the xe2x80x9cstop and goxe2x80x9d type, the coating product being changed in a period of time corresponding to the space separating two consecutive vehicle bodies, the time available being all the shorter as the speed of conveyance increases.
In addition, the losses of coating products during filling of the reservoir and priming of the sprayer should be minimized, as well as the consumption of cleaning product necessary to avoid a mixture and/or pollution between two coating products used successively with the sprayer.
Such consumption should therefore be reduced to a maximum while conserving systems of supply of coating product and of cleaning product which are reliable and of moderate cost.
It is a more particular object of the present invention to overcome these problems and respond to the requirements by proposing a novel process and a novel station for changing coating product, which allow a rapid change of product, while the quality of cleaning effected remains optimum and the consumption of cleaning product and of coating product is substantially reduced with respect to known systems.
To that end, the invention relates to a process for changing product in an installation for spraying coating product, comprising at least one robot, adapted to displace a first sprayer and a first reservoir associated therewith opposite objects to be coated,. This process which includes:
a step of bringing this reservoir towards a suitable area of a cleaning/filling station,
a step of separating a first sub-assembly comprising the first reservoir and the first sprayer with respect to the robot,
a step of connecting with the robot a second, similar, sub-assembly comprising a second reservoir and a second sprayer, this second sub-assembly being adapted to be used for spraying coating product during cleaning and/or filling of the first reservoir and the first sprayer, and
a step of cleaning and/or filling the first reservoir and the first sprayer in the said area;
is characterized in that it comprises the steps of:
positioning a coating product supply unit equipped with a plurality of outlets by displacing this unit in a first direction, so that a predetermined outlet of this unit is disposed opposite the first sub-assembly;
displacing, in a second direction substantially perpendicular to the first direction, a structure defining at least two receiving areas of said sub-assemblies, so as to reach a position of connection of the sub-assembly with said unit.
Thanks to the invention, one can proceed with cleaning the first reservoir and filling it with fresh coating product in masked time. Likewise in masked time, one proceeds with the cleaning of the sprayer and priming thereof with the new coating product, with the result that the only steps of the cleaning/filling process which are to be taken into account in the calculation of the duration of the chance of product are the steps of separation of the first sub-assembly from and of connection of the second sub-assembly on the arm of the robot.
The fact of using a coating product supply unit equipped with a plurality of outlets makes it possible to dispense with the use of a common collector, which would have to be cleaned when two different coating products are successively used, this making it possible to reduce the consumption of products, particularly by the elimination of a pipe between a product change block and the cleaning/filling station. The positioning of this second unit with respect to the sub-assembly also makes it possible to use a single unit of this type for the selective supply of the first or of the second sub-assembly.
According to advantageous aspects of the invention, the process incorporates one or more of the following characteristics:
The operations of separation of the first sub-assembly with respect to the robot and of connection of the second sub-assembly with the robot are carried out within an area of activity of the robot while the operations of positioning the first sub-assembly and the second unit and the operations of connection, of cleaning and/or of filling are carried out outside this area of activity thanks to a movement of the structure in two orthogonal directions. Area of activity is understood to mean the volume in which the arm of the robot is capable of moving.
The process comprises a step consisting of displacing, in the first direction, said structure, so as to place the area of this structure including this sub-assembly opposite a cleaning product supply unit, the displacement of this structure in the second direction making it possible to reach a connection position of the sub-assembly with this cleaning product supply unit. Thus, the positioning of the first sub-assembly opposite the cleaning product supply unit makes it possible to use a single unit for alternately cleaning the first or the second sub-assembly which are each located in a receiving area devoted thereto.
The process consists in connecting at least one of the above-mentioned units to the sub-assembly by displacement of connection means in the second direction.
The process consists in continuously supplying the first sub-assembly with air for forming a bearing and/or with air for driving a turbine of the sprayer as soon as it is deposited in a reception area and until it is withdrawn therefrom. This makes it possible to avoid a risk of xe2x80x9csqueezingxe2x80x9d an air bearing in the event of sudden rupture of its supply upon disconnection and re-connection of the sub-assembly with respect to the arm of the robot. The fact of permanently supplying a turbine with driving air enables its speed of rotation to be maintained at a value of the same order of magnitude as the speed used for spraying. The time for resumption of speed of the turbine after re-connection of the sub-assembly on the robot arm after the cleaning/filling operation is thus saved. In practice, the turbine of the sprayer of the first sub-assembly is continuously maintained in rotation during the operations of positioning, connection, cleaning and/or filling.
The invention also relates to a product changing station in an installation for spraying coating product, which carries out the process described hereinabove. This station comprises at least two areas for cleaning/filling the reservoir, adapted each to receive a sub-assembly formed by a reservoir and a sprayer while this sub-assembly is disconnected from the robot, means for cleaning and/or filling the reservoir and/or the sprayer in each of these areas being provided. These areas are adapted to be brought into a position of connection of a sub-assembly disposed in one of them with the above-mentioned cleaning and/or filling means, while these means comprise at least one unit mobile in a first direction, provided with a plurality of outlets and adapted to dispose a predetermined outlet of this unit in a position of connection to the sub-assembly.
The mobility of the areas for receiving the sub-assemblies and the second unit makes it possible to reduce the lengths of the pipes supplying cleaning product and/or coating product, i.e. the parts in course of manufacture and the quantities lost upon each change of product. The connection may then take place by the displacement of the appropriate area mentioned above, perpendicularly to the first direction.
According to advantageous aspects of the invention, the station incorporates one or more of the following characteristics:
The areas of reception of sub-assemblies are defined by a structure mobile with respect to a support in a first direction while this support is mobile with respect to the robot in a second direction substantially perpendicular to the first direction.
The cleaning and/or filling means comprise a first unit adapted to deliver to the sub-assembly at least one cleaning fluid, this first unit being disposed opposite the sub-assembly in its position of connection, and a second unit, adapted to deliver to the sub-assembly a predetermined coating product, this second unit being mobile with respect to the first unit. The station therefore allows a positioning of each of the areas of reception of the sub-assemblies opposite the first unit and the second unit with respect to the first unit, in order to allow a connection of each of these units with the sub-assembly received in the area in question. In that case, the second unit advantageously comprises a plurality of modules supplied with coating product and adapted to be selectively connected to the sub-assembly, these modules being juxtaposed in a direction of displacement of the second unit. Thanks to this arrangement, an indexation of the position of the second unit makes it possible to use one or the other of the above-mentioned modules with a view to supplying the sub-assembly with coating product. Certain of these modules may be supplied by means of circuits for circulation of product, for the coating products most often used, while at least one other module is supplied from at least one coating product changing block, for the coating products used least often. In that case, the other module is advantageously provided with means for connection to an element supplied with coating products from the product changing block, this element being mobile in a direction substantially perpendicular to the direction of displacement of the second unit.
The first unit may comprise a connection element applied in the direction of the sub-assembly with a view to their connection.
Means are provided, for supplying air forming a bearing and/or air driving a sprayer turbine of a sub-assembly in place in one or the other of the receiving areas. In that case, a sensor for detecting the presence of a sub-assembly in each of the areas is advantageously used.
The invention will be more readily understood and other advantages thereof will appear more clearly on reading the following description of an embodiment of a product change station and of its process of implementation according to the invention, given solely by way of example and made with reference to the accompanying drawings, in which: